22 militants killed in air strike on al Qaida-affiliated headquarters in northern Syria

In this image posted on the Twitter page of Syria's al-Qaida-linked Nusra Front on Friday, April 1, 2016, shows smoke billowing as Nusra Front fighters attack the northern village of al-Ais in Aleppo province

At least 22 militants have been killed in an air strike on an al Qaida-affiliated headquarters in northern Syria, a monitoring group has said.

The Britain-based Syrian Observatory for Human Rights said jets thought to belong to the Syrian or Russian air forces targeted the headquarters of Jund al-Aqsa, an extremist group that fights alongside the Nusra Front, al Qaida's affiliate in Syria, on Sunday night.

A media outlet belonging to the Lebanese militia Hezbollah said the strike killed the Nusra Front's official spokesman, Radwan Namous, also known as Abu Firas al-Souri, and his son.

Hezbollah has sent thousands of its fighters to fight alongside Syrian government forces in the country's five-year civil war.